Screen cloth tightening means



Jan. 1944- c. s. LINCOLN SCREEN CLOTH TIGHTENING MEANS Filed July 30, 1942 5, llll llllllllT Illlllll Patented Jan. 4, 1944 SCREEN CLOTH TIGHTENING MEANS v Charles S. Lincoln, Wauwatosa, Wis., assignor to Allis-Chalmers Manufacturing Company, Milwaukee, Wis., a corporation of Delaware Application July 30, 1942, Serial No. 452,829

7 Claims.

This invention relates generally to screening apparatus and more particularly to the construction of the screen cloth deck of vibrating screens and the tensioning means therefor.

The vibrating screens heretofore employed generally embody only a single screen cloth section which is secured at the feed and discharge ends of the screen frame by adjustable clamping bars or the like efiective to tension and/or stretch the cloth longitudinally of the frame; the screen cloth being supported intermediate its ends by a series of longitudinally spaced transverse cross members arranged in progressively displaced relation to provide in effect a crowned support over which the cloth is stretched. However, the screen cloth supporting and tensioning means heretofore employed are not satisfactory for use on long screens since the wear on the screen cloth is not uniform throughout its length (the wear being greatest at the material receiving end of the screen and progressively dimensioning toward the discharge end thereof as the quantity of undersized material passing through the screen decreases) which results in local stretching and variations in mesh size, thereby necessitating frequent replacement of the entire section in order to obtain a desired and uniform screening action.

It is therefore the object of this invention to provide an improved deck construction for vibrating screens which will effect one or more of the following results and/or advantages: 1) eliminate replacement of the screen forming the entire deck when only a portion of the screen becomes worn: (2) permit rearranging portions of the screen deck to effect a more uniform wear throughout its length; (3) permit variably tensioning different longitudinal sections of the screen deck; and (4) a durable and simplified construction which can be manufactured, installed and serviced with a minimum of time and expense.

In accordance with this invention, one or more of the aforementioned advantages and results may be obtained by forming a deck with a plurality of similar and preferably interchangeable screen sections disposed in end to end relation and providing means intermediate the ends of the deck for simultaneousl adjusting the longitudinal tension of two adjacent screen sections.

The invention accordingly consists of the details of construction. combinations of elements and arrangements of parts as more fully set forth in the accompanying claims and in the detailed description, reference being had to the accompanying drawing, in which:

Fig. 1 is a plan view of a screen deck embodying the invention;

Fig. 2 is a vertical section taken on line IIII of Fig. 1;

Fig. 3 is an enlarged partial section illustrating the means for simultaneously adjusting the longitudinal tension of two adjacent sections;

Fig. 4 is a side elevation of the structure shown .in Fig. 3;

Fig. 5 is a plan view of a modified screen section adjusting means; and

Fig. 6 is a side elevation of the structure shown in Fig. 5 with parts broken away to better show the construction.

Referring particularly to Figs. 1 and 2, it is seen that a screen deck construction embodying the invention may include a frame I comprising spaced opposed longitudinally extending side members 2, longitudinally spaced end members 3 interconnecting said side members, and an intermediate vibrating mechanism support 4 mounted on brackets 6 carried by opposed wall portions of the side members 2. A conventional vibrating mechanism 1 is suitably mounted on the support t and the entire structure is suspended from a fixed structure (not shown) by means of four vertically extending rods 8.

A plurality of screen cloth sections, including for purposes of illustration end sections 9 and I2 and an intermediate section II, are mounted in said frame in longitudinal relation for the passage of material successively thereover by means of the screen cloth clamping plates l3 and I ll adjustably attached to the end members 3 and two intermediate transverse screen hook engaging rod members It and I! which are supported in longitudinally spaced relation by opposed wall portions of the side members 2. Each of said screen cloth sections has its opposite ends or edges provided with oppositely bent hooks I 8 and It adapted to engage the clamping plates l3 and I and the transverse rod members l6 and I! in the manner shown in Fig. 2. Rod'members l6 and I! are necessarily spaced apart and from said clamping plates distances approximately equal to the length of the screen cloth section which is to be stretched thereacross and each of said sections is additionally supported'intermediate its ends by a series of longitudinally spaced cross members 2| which are preferably provided with screen cloth engaging buffer strips 22 formed of rubber or other suitable material and which are arranged in progressively displaced relation to provide in effect a crowned support over which the cloth is stretched. In this connection, the

transverse members It and H are preferably spaced equal distances from each other and from the clamping plates i3 and It in order to reduce manufacturing costs and render the screen cloth sections interchangeable in the event of non-uni form wear thereon. Material passing over the deck is prevented from falling between the side edge of the screen cloth and the side members 2 by meansof resilient seal strips '23 which are attached to thesidemembers 2 in anysuitable manher (not shown) with their lower edges in engagement with the upper surface of the side margins of the screen cloth sections. fI-hedischargeend of the frame I is preferably-provided with a rearwardly extending apron as which shields the clamping plate l4 and. the adjustingmechanisni therefor and directs the material leaving the screen cloth section 12 away from the screen frame.

Clamping plates 13 and M, are each mounted to vary the longitudinal tension of the screen sections hooked thereon by meansof .a plurality :of spaced bolts 26 each-of which(extend-s through the adjacent end member 3 and has one end at .tached to the adjacent clamping plate and its other exposedendsurrounded by .a compression spring 2?! interposed between its head and the outside wallsurface of said .end member. The transverse member I1 is also mounted .forsimul- .taneously varying the longitudinal tension of two screen cloth sectionsli and 4.2 by means of rectangular plates 28 which are secured to theends of the member .llandare .slidably disposed in rectangular openings itiormedin'opposed wall portions .of the side members T2 for longitudinal movement relative thereto. The plates 28 are slidably retained in said openings .bvmeans of larger plates 3! which may be .removably secured thereto and .in sliding engagement with the outside .wall surface of the side members by any suitable means such was bolts Z32. Longitudinal .adjustment of the .plates .3! and therebythe .plate 28 and member H .iseffected bymeansof bolts33 which extendthrough alined openings provided in opposed walltportions of the projections 34 and secured \to the plates 3-! and side members 2, respectively, as is clearly shown in Figs. 1, 3 and .4. .Itshouldnow be apparent that the tensioning devices hereinbefore described provide means .for readily varying the longitudinal tensionla) .of endsection 9 by adjustingclamping plate .53, (b) of intermediate section H and end section i2 .by longitudinally adjusting vmember l1, and c of. end section 12 by adjusting clamping plate is. longitudinaLadjnstment of member illina direction effective to increase the tension of section Iisimultaneouslyeffects .a decrease in the tensioniof section 1.2 therebynecessitating.an .adjustment .of theclainping plate lid ,if the tension of section 12 is .to .be increased or maintained as .it was prior .to said adjustment of member H. Ethesame .is true when member .IT .is .adjusted .totefiect adecrease in the tension of section I i andinthisconnection, it should also be obvious lthatgif desired, the various sections may be given different degrees of tension.

.ReierringtoIEigs. strand '5 in which like numetals are used todesignate the same or similar parts, itis seen that transversemember .H is modified "ioroangular adjustment thereby rendering same .efiective to simultaneously increase or decrease lthe'tensionof sections H and -l2. Said modificationoons'istsfin employing a round shaft 3 1 having a squared end 63 for .rotating same Obviously, a

and enclosing said shaft in a tube 31 which is removably secured to the shaft for rotation therewith by any suitable means, such as pins 38, and which has welded thereto oppositely extending screen hook receiving projections 39 adapted to be engaged by the hooked ends [9 and It of screen sections II and I2, respectively. The shaft 34 is supported for angular movement in 'alinedholes providediin opposed wall portions of the side'members 2 and the squared end of the shaft extends beyond the outer wall portion of the adjacent side member a sufficient distance to mount thereon a ratchet wheel 4| having its hub portion secured to said shaft for angular movement therewith by means of a set screw 42. Projections 39 are so arranged that a clockwise movement of shaft 34 and tube 31 (the shaft, tube and ratchet wheel move as a unit) simultaneously increases the longitudinal tension of sections H and I2. Movement of the shaft in .a counterclockwise direction is prevented by .means .of .a pawl 43 which is prevented :from be- .ing disengaged from said -wheel by means .of "a removable belt or ,pin M. Tube :31 is approximately equal in length to the :distance between the side members 2 and this modified construction permits the tensioning member -to be mounted in and removed from an -existing frame since if the pins 38 are removed, the'shaft can be withdrawn from the tube and the'latter can then be placed or removed :from between the-side memberl'asdesired. This procedure should now be obvious and a further description inthis-con- .nection is deemed unnecessary 'for a complete understanding of the invention.

Themodified censtructionshown in Figs. 4 "and =5 affords all of the advantages inherent in the construction shown in Figs. l, 2 and 3 and :is preferable in installations in which .a simultaneous increase or decrease in the tension of the screen sections attached thereto is desired. The invention is applicable to screendeck constructionslembodying two or more screen sectionsregardless of whether or not the screen :sections are made interchangeable and it should therefore .be understood that, although the invention is I disclosed in connection with a deck embodying three-screen sections, it is not intended-to limit the invention to the exact details of deck and tensioningconstructions herein shown and described for purposes of illustration, as various modifications within the scope of the appended claims may occur to persons skilled in :the art.

"It'is claimed and desired to secure by Letters Patent:

1. A screen .deck comprising :side walls, a plurality of transverse members including end membersxand'at least two intermediate'members connecting said sidewalls, a pluralityof screen cloth sections-including end sections and atleast one intermediate section disposed in longitudinal relation for the passage of material successively 'thereover with each section spanning and being supporting'ly connected with two of said transverse members, each said intermediate member supporting the adjacent ends of two said screen sections and means operably engaging said side walls and at least one said intermediate member to move said intermediate member in a manner effective to change the longitudinal tension .of said end andintermediate sections.

2. A screen deck comprising longitudinal side walls, a plurality of transverse members include ing end members and -.at1least one .Zintermediate member connecting said side walls a plurality of screen cloth sections disposed in longitudinal relation for the passage of material successively thereover with the proximate ends of two adja cent sections being supportingly connected with said intermediate transverse member, and means operably engaging said side walls and said intermediate member and actuable to move said intermediate member in a manner effective to simultaneously adjust the longitudinal tension of said two adjacent sections.

3. A screen deck frame for mounting a plurality of screen cloth sections in longitudinal relation for the passage of material successively thereover comprising longitudinal side walls, a plurality of transverse members including end members and at least one intermediate member connecting said side walls, said end members being provided with means for attaching the end of a screen section thereto and said one intermediate member being provided with means for attaching the proximate ends of two adjacent screen sections thereto, and means operative to move said one intermediate member in a manner efiective to move said proximate ends of said screen sections in opposite directions to simultaneously increase or decrease the longitudinal tension of the two adjacent screen sections attached thereto.

4. A screen deck frame for mounting a plurality of similar individual screen cloth sections in longitudinal relation for the passage of material successively thereover comprising longitudinal side Walls, a plurality of transverse members including end members and at least one intermediate member connecting said side walls and being provided with means for attaching the ends of screen sections thereto, proximate ends of two adjacent said screen sections being attached to each said intermediate member and means for longitudinally adjusting an intermediate one of said transverse members comprising oppositely disposed slots in said side walls, a plate substantially covering each of said slots and being connected with said transverse member for movement therewith, and means mounted on said side Walls for adjusting the longitudinal position of said plates to simultaneously vary the tension of said two adjacent screen sections operatively connected thereto.

5. A screen deck comprising longitudinal side walls, a plurality of similar individual screen cloth sections, a plurality of equally spaced transverse members including end members and at least one intermediate member connecting said side walls and interchangeably mounting said screen cloth section in longitudinal relation for the passage of material successively thereover at least one said intermediate member having mounted thereon proximate ends of two adjacent said screen sections, and adjusting means for rotating said intermediate member in a manner effective to simultaneously tension said two adjacent screen sections.

6. The structure of claim 5 in which said adjusting means comprises means operatively engaging said side Walls to retain said adjusting means in adjusted position against the tension of said screen sections.

7. A screen deck comprising side walls, a plurality of transverse members including end members each having a free edge and at least one intermediate member having a pair of oppositely extending free edges, a plurality of separate readily reversible and interchangeable screen cloth sections each provided with a rigid hook strip at each end thereof, said sections being disposed in longitudinal relation for the passage of material successively thereover with each section spanning and being supportingly connected with two of said transverse members by engagement of said hook strips with oppositely extending said free edges, each said intermediate membar so supporting adjacent ends of two said screen sections, and means operably engaging said side walls and an intermediate member to adjust the position of said intermediate member for simultaneously changing the longitudinal tension of the two adjacent screen sections supported thereon.

CHARLES S. LINCOLN. 

